Method, apparatus, and computer program product for signaling allocation of neighbor cells

ABSTRACT

A method, user equipment, network device, and software product employ indicators from a plurality of respective cells to indicate a difference, if any, regarding allocation in the respective cell as compared to neighbor cells. Mobility measurements are then performed according to the indicators, and also on the basis of configuration of a cell where the measurements are performed.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Application60/927,362 filed 2 May 2007.

FIELD OF THE INVENTION

The invention relates to the field of wireless telecommunications. Moreparticularly, the present invention pertains to cell allocation.

BACKGROUND OF THE INVENTION

The telecommunications industry is in the process of developing a newgeneration of flexible and affordable communications that includeshigh-speed access while also supporting broadband services. Manyfeatures of the third generation (3G) mobile telecommunications systemhave already been established, but many other features have yet to beperfected.

One of the systems within the third generation of mobile communicationsis the Universal Mobile Telecommunications System (UMTS) which deliversvoice, data, multimedia, and wideband information to stationary as wellas mobile customers. As can be seen in FIG. 1, the UMTS architectureconsists of user equipment 102 (UE), the UMTS Terrestrial Radio AccessNetwork 104 (UTRAN), and the Core Network 126 (CN). The air interfacebetween the UTRAN and the UE is called Uu, and the interface between theUTRAN and the Core Network is called Iu.

Evolved UTRAN (EUTRAN) is meant to take 3G even farther into the future.EUTRAN is designed to improve the UMTS mobile phone standard in order tocope with various anticipated requirements. EUTRAN is frequentlyindicated by the term Long Term Evolution (LTE), and is also associatedwith terms like System Architecture Evolution (SAE).

Information about LTE can be found in 3GPP TR 25.913 (V7.2.0, December,2005), Requirements for Evolved UTRA (E-UTRA) and Evolved UTRAN and alsoin 3GPP TR 25.813 (V0.1.0, November 2005), Evolved UTRA and UTRAN—Radiointerface protocol aspects, both of which are incorporated herein byreference in their entirety. UTRAN and EUTRAN will now be described insome further detail.

The UTRAN consists of a set of Radio Network Subsystems 128 (RNS), eachof which has geographic coverage of a number of cells 110 (C), as can beseen in FIG. 1. The interface between the subsystems is called lur. EachRadio Network Subsystem 128 (RNS) includes a Radio Network Controller112 (RNC) and at least one Node B 114, each Node B having geographiccoverage of at least one cell 110. As can be seen from FIG. 1, theinterface between an RNC 112 and a Node B 114 is called Iub, and the Iubis hard-wired rather than being an air interface. For any Node B 114there is only one RNC 112. A Node B 114 is responsible for radiotransmission and reception to and from the UE 102 (Node B antennas cantypically be seen atop towers or preferably at less visible locations).The RNC 112 has overall control of the logical resources of each Node B114 within the RNS 128, and the RNC 112 is also responsible for handoverdecisions which entail switching a call from one cell to another orbetween radio channels in the same cell.

In UMTS radio networks, a UE can support multiple applications ofdifferent qualities of service running simultaneously. In the MAC layer,multiple logical channels can be multiplexed to a single transportchannel. The transport channel can define how traffic from logicalchannels is processed and sent to the physical layer. The basic dataunit exchanged between MAC and physical layer is called the TransportBlock (TB). It is composed of an RLC PDU and a MAC header. During aperiod of time called the transmission time interval (TTI), severaltransport blocks and some other parameters are delivered to the physicallayer.

Generally speaking, a prefix of the letter “E” in upper or lower casesignifies the Long Term Evolution (LTE). The E-UTRAN consists of eNBs(E-UTRAN Node B), providing the E-UTRA user plane (RLC/MAC/PHY) andcontrol plane (RRC) protocol terminations towards the UE. The eNBsinterface to the access gateway (aGW) via the S1, and areinter-connected via the X2.

An example of the E-UTRAN architecture is illustrated in FIG. 2. Thisexample of E-UTRAN consists of eNBs, providing the E-UTRA user plane(RLC/MAC/PHY) and control plane (RRC) protocol terminations towards theUE. The eNBs are connected by means of the S1 interface to the EPC(evolved packet core), more specifically to the Mobility ManagementEntity (MME). The S1 interface supports a many-to-many relation betweenMMEs and eNBs. The MME in the example of FIG. 2 is one option for theaccess gateway (aGW).

In this example of E-UTRAN, there exists an X2 interface between theeNBs that need to communicate with each other. The eNB may hostfunctions such as radio resource management (radio bearer control, radioadmission control, connection mobility control, dynamic allocation ofresources to UEs in both uplink and downlink), selection of a mobilitymanagement entity (MME) at UE attachment, scheduling and transmission ofpaging messages (originated from the MME), scheduling and transmissionof broadcast information (originated from the MME or O&M), andmeasurement and measurement reporting configuration for mobility andscheduling. The MME may host functions such as the following:distribution of paging messages to the eNBs, security control, IP headercompression and encryption of user data streams; termination of U-planepackets for paging reasons; switching of U-plane for support of UEmobility, idle state mobility control, System Architecture Evolution(SAE) bearer control, and ciphering and integrity protection of NASsignaling.

According to recent developments in this field, the user equipment (UE)can measure any reference signal (RS) from a first antenna (#1) and asecond antenna (#2), with the exact pilot/frame structure given in 3GPPTS 36.211 V. 1.0.0 (2007 March) Physical Channels and Modulation(Release 8) which is incorporated herein by reference in its entirety.Orthogonal Frequency Division Multiplexing (OFDM) symbols bearing thisreference signal (RS) occur 4 times per unicast sub-frame and only oncein Multicast Broadcast Single Frequency Network (MBSFN) sub-frames. Theaccuracy and reliability of mobility measurements depends on the numberof RS resource elements eligible for measurements, and on the UEawareness of presence or absence of some RS resource elements (e.g. inMBSFN sub-frames). These mobility measurements have to be carried out onRS resource elements of the cell on which the UE is camping on, as wellas on corresponding neighbor cells.

Various solutions to this problem have been attempted. For example, onetechnique is to signal full MBSFN sub-frame allocation of a cell on thiscell's primary Broadcast Channel (P-BCH). However, that technique isvery costly from the overhead point of view, because the P-BCH is a veryrobust channel and each P-BCH bit consumes a non-negligible part of acell's capacity. Furthermore, for measuring RS from neighbor cells, thisrequires that the P-BCH from neighbor cells be received before andduring measurements which might be unreliable and adds extra complexity.

A second technique is to measure the RS only in the first OFDM symbol ofeach sub-frame. However, according to that technique, the number of RSelements eligible for measurements is always reduced by a factor of 4,which will incur measurement inaccuracy.

A third technique is to signal a per carrier MBSFN/non-MBSFN indication.Therefore, in the MBSFN case, only the first RS OFDM symbol of eachsub-frame would be used (see second technique described above), and inthe non-MBSFN case up to 4 RS OFDM symbols could be used. This meansthat in the latter case all available and eligible RS elements can bemeasured in unicast carriers. However, according to this thirdtechnique, the number of RS elements eligible for measurements isreduced by a factor of 4 in any mixed MBSFN/unicast carrier (includingcarriers where the MBSFN area includes only a couple of cells orincluding carrier-wide MBSFN area(s)).

SUMMARY OF THE INVENTION

Although the present invention is applicable in the context of the LTE,its principles are not limited to LTE, and instead may also beapplicable to various other current and future wirelesstelecommunications systems. Throughout this application, the generalterm “base station” will be understood to include an eNB, a Node B, orany other network element that serves a purpose analogous to a basestation of the UTRAN.

This invention is related to the standardized Long Term Evolution of3GPP. More specifically it considers mobility measurements taking intoaccount the possibility to multiplex unicast and multicast/broadcasttraffic within one frequency carrier.

According to recent developments in this field, time divisionmultiplexing (TDM) of Multimedia Broadcast Multimedia Services (MBMS)and unicasting of data channel (Physical Downlink Shared Channel PDSCH)are done on a sub-frame basis. The unicast control channel (PhysicalDownlink Control Channel or PDCCH) together with downlink unicast pilot(cell specific RS) can be TDM multiplexed with MBSFN in the samesub-frame (so-called MBSFN sub-frame) in case of a mixed MBSFN orunicast carrier. In such MBSFN sub-frames, the PDCCH (with cell-specificpilot) is transmitted in the first, or in the first two, OFDM symbolsand MBSFN (multi-cell traffic and pilot) is transmitted in the rest ofthe sub-frame's OFDM symbols. Furthermore, according to recentdevelopments, MBSFN should not be transmitted in sub-frame #0 and #5(i.e. Synchronization Channel or SCH sub-frames), so that UE canconfidently use cell-specific RS at least in these sub-frames formeasurements.

MBSFN symbols in MBSFN sub-frames can also contain cell common pilotsbut they cannot be used for unicast handover measurements.

Providing full information regarding MBSFN or unicast sub-frameallocation in neighbor cells via own cell would be costly from theoverhead or signaling point of view. The present invention thereforeincludes an efficient method to provide information about MBSFN orunicast allocation in neighbor cells, and to maximize the accuracy ofmobility-related neighbor cell measurements by maximizing the number ofRS resource elements eligible for UE mobility measurements of neighborcells.

According to the present invention, each cell transmits an indicator(preferably only one bit) of the difference in unicast or MBSFNsub-frame allocation between the own cell and neighbor cells. Theindicator is broadcast on a common channel preferably a broadcastcontrol channel. The indicator is set and signals whether unicast orMBSFN allocation in neighbor cells is the same or not compared to theown cell.

It should be noted that unicast or MBSFN allocation in many scenarioswill be the same in the own cell and in neighbor cells. These scenariosinclude: Unicast carriers (and MBSFN dedicated carriers), Unicast/MBSFNcarriers with PLMN-wide MBSFN area(s), non-PLMN-wide MBSFN area(s)deployed over large geographical regions in unicast/MBSFN carriers, andUnicast areas in unicast/MBSFN carriers with non-PLMN-wide MBSFNdeployments (PLMN stands for Public Land Mobile Network). In addition,inter-node signaling can be used to automate setting of the indicator.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a UTRAN network.

FIG. 2 shows an LTE architecture.

FIG. 3 where the indicator would be the same for all cells of a Node B:neighbor cells of Node B 1 have different unicast or MBSFN allocations.

FIG. 4 presents the case when all cells are unicast, the indicator isoff.

FIG. 5 presents the case when all cells are mixed unicast or MBSFN andhave the same unicast or MBSFN allocation (i.e. the cell belong to thesame MBSFN area(s)) so the indicator is off.

FIG. 6 is a flow chart showing a method according to a embodiment of thepresent invention.

FIG. 7 is a block diagram showing a system according to a embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of the present invention will now be described.This is merely to illustrate one way of implementing the invention,without limiting the scope or coverage of what is described elsewhere inthis application.

As mentioned, each cell transmits an indicator (preferably only one bit)of the difference in unicast or MBSFN sub-frame allocation between theown cell and neighbor cells. The indicator is broadcast on a commonchannel, preferably a dynamic broadcast channel. The indicator is setand signals whether unicast or MBSFN allocation in neighbor cells is thesame or not compared to the own cell

An example of the present invention is shown in FIG. 3, where theindicator would be the same for all cells of a Node B: neighbor cells ofNode B 1 have different unicast or MBSFN allocations. In consequence,the indicator broadcasted in the cells of Node B 1 is on. Node B 1 isaware of MBSFN or unicast allocation in cells of the group of (6)surrounding Node Bs (marked by bold line). Neighbor cells of Node B 2have the same MBSFN or unicast allocations, and therefore the indicatorin the cells of Node B 2 is off (same for Node B 3). The criss-crosspattern in FIG. 3 indicates an MBSFN area. Observe that the indicator ineNode B 4 can also be set off, in case the MBSFN sub-frames location inneighbor cells of this Node B is a sub-set of the MBSFN sub-frames ineNode B 4 i.e. the UEs in cells of Node 4 know that surrounding cellstransmit the same or more unicast sub-frames

If the indicator is set to a first value, e.g. “0” (e.g. unicast carrierc.f. FIG. 4, interior of MBSFN area(s) c.f. FIG. 5), this means thatunicast or MBSFN allocation (i.e. the location of MBSFN and/or unicastsub-frames) in neighbor cells is the same as in the own cell. The UEaction will be such that the UE can use the RS resource elementseligible for the Reference Signal Received Power (RSRP) measurements ofneighbor cells corresponding to the ones used for measurements in theown cell. The eligible RS resource elements in neighbor cells arederived on the basis of the unicast/MBSFN allocation of the own cell

However, if the indicator is set to a second value e.g. “1” (e.g. borderof MBSFN area(s) c.f. FIG. 3), this means that a unicast or MBSFNallocation in neighbor cells is different comparing to the own cell. TheUE action will be such that the UE falls back to measure neighbor cellsusing only the RS resource elements in the first OFDM symbol in eachsub-frame together with all RS resource elements in SCH-sub-frames(regardless of the fact if the UE is aware of the cyclic prefix lengthin these first OFDM symbols)

Furthermore, there may be inter-node signaling so that each cell/eNode Bcan determine if MBSFN/unicast allocation in its neighbor cells/Node Bsis the same or not and set the indicator value automatically. Thissignaling can be between neighbor eNode Bs (the X2 interface) and wouldexchange the information regarding each others MBSFN/unicastallocations. Also, this signaling can be between a master node (e.g.Multi-cell Coordination Entity) and groups of neighbor eNode Bs toinform Node Bs/cells if the MBSFN/unicast allocation in neighbor cellsis the same or not (alternatively informing about the exactMBSFN/unicast allocation of neighbor cells/eNode Bs).

From the inter-cell power control point of view, there must be a notionof neighbor cells (detectable and measured by serving UEs) exchangingoverload indicators over the X2 interface. Therefore, it may bebeneficial and simple if the same group can be used to define neighborcells being aware of each other MBSFN/unicast allocation.

Prior to Dynamic Broadcast Channel (D-BCH) or MBMS Control Channel(MCCH) reception, the UE might be not aware of the MBSFN/unicastallocation in the own cell e.g. during initial cell search. Inconsequence inter-sub-frame channel estimation for D-BCH demodulationmight be constrained. Therefore, it might be beneficial not to constraininter-sub-frame channel estimation by placing the D-BCH adjacently tounicast sub-frames (e.g. SCH sub-frames).

Advantages of the above preferred embodiment include low overhead, andno need to constantly read the Broadcast Channel of neighbor cellsduring measurements. Furthermore, the number of RS resource elementseligible for mobility measurements of neighbor cells is increased intypical deployment scenarios (this increases the measurement accuracyand decrease the number of erroneous handovers and cell reselections).Also, the indicators in each cell can be set automatically if inter-nodesignaling of MBSFN/unicast allocation is specified (alternativelysetting of the indicators can be operator or implementation-specific).Additionally, there is no need to additionally define groups of neighborcells or Node Bs if the groups of Node Bs or cells exchanging overloadindicators over the X2 interface for inter-cell power control are reused(alternatively the definition of groups can beoperator/implementation-specific).

Alternatively, if some UEs are not aware of MBSFN or unicast allocationin the own cell the following solution can be adopted: the indicator cantake more than two values/states (e.g. 2 bits). Two values are used bythe UEs being aware of MBSFN or unicast allocation as described in thepreferred implementation, the remaining two values are used to signal tothe UEs being not aware of MBSFN or unicast allocation in the own cellwhether neighbor cells are unicast or mixed MBSFN or unicast cells.

The signaling between the eNode B and the UE will have to be specifiedand implemented in the eNode B and in the UE. Furthermore, theinterpretation of the signaling and relevant behaviour will beimplemented in the UE. Finally, also corresponding eNode B to eNode Bsignaling or an information exchange involving a central node will beneeded.

The present invention includes a cellular mobile communication system(e.g. LTE) in which base stations (e.g. eNode Bs) provide a beaconsignal (e.g. reference signal) for mobile stations (e.g. UEs) in theircells and in which this beacon signal is provided in specific timeperiods (e.g. reference signal symbols), i.e. not continuously and thereare at least 2 phases: phase A (e.g. a unicast sub-frame) in whichbeacon signals are provided N times (e.g. N=4) over time interval A atfixed locations; and phase B (e.g. MBMS sub-frame) in which beaconsignals are provided M times (e.g. M=1) over time interval B at fixedlocations.

Each cell can either operate in phase A only, in phase B only, or in acombination of phases A and B for which it is cell-specific how manyphases A and how many phases B follow each other. The present inventionconsiders such a system and provides a means for mobile stations tocarry out measurements of these beacons in the serving (own) and theneighbor cells by: exchange of cell specific lists of the sequences ofphases A and B used for a determined time period; exchange of theselists between neighbor cells/base stations via network interfaces;providing of corresponding information to the UEs by its serving cell sothat these UEs know when to measure which beacon signal of own andneighbor cells.

The present invention also includes modifications of the system justdescribed. The system may be such that the M time positions form asubset of the N time positions. Also, the system may be such that cellsare synchronized or the UE knows the cell timing (e.g. via reading thesynchronization channel).

The present invention also includes either of the systems justdescribed, for which the “corresponding information” is provided in aform of a complete or reduced list for serving and neighbor cells (e.g.cell 1: x times phase A, y times phase B; cell 2: q times phase A, rtimes phase B; cell 3: u times phase B, v times cell A, w times phase B;or e.g. reduced: xA, yB/qA, rB/uB, vA, WB), or as a list only from theserving cell either in a broadcast manner (e.g on BCH) or in mobilestation specific way.

The present invention also includes the systems just described, forwhich the “corresponding information” is provided for the serving cellin the form of a list from the serving cell either in a broadcast manner(e.g on BCH) or in mobile station specific way, or is provided for allpredefined neighbor cells in a form of an indicator sent from theserving cell which indicates whether the serving cell is using the samephase A/phase B setting as a predefined set of neighbor cells or not.This indicator could be one indicator per neighbor cell or one indicatorfor all cells.

The present invention also includes the systems just described, forwhich the M time positions form a subset of the N time positions, sothat if the indicator indicates that the setting of a neighbor cell isdifferent from the serving cell the UE could measure at least on thesubset of beacon signals.

If a base station is controlling all its cells in the same way withrespect to the sequence of phases A and B, then the considerationsrelated to the various systems just described could also be implementedper serving and neighbor base station instead of per serving cell andneighbor cell.

As seen in FIG. 6, one method 1600 of the present invention begins byreceiving 605 a discontinuous beacon signal from a base station, thebeacon signal having two possible phases. This occurs at a plurality ofbase stations. Then an indicator is received 610 from the base station,indicating the difference at the bases station's cell, as compared toneighboring cells, regarding each cell's use of the two possible phases.Subsequently, mobility-related neighbor cell measurement is performed620 using the indicator, and also using cell configuration information.

An embodiment for performing part of this method is shown in FIG. 7. Thesystem 700 includes a mobile communication device 710 and a base station720. A processor 735 in the base station calculates an indicatorindicative of differing allocation in different cells, and provides theindicator to a transceiver 740 which transmits the indicator to themobile device 710. The mobile device includes a transceiver 725 forreceiving the indicator, and a measurement module 730 for performingmobility-related measurements using the indicator.

Several further concepts associated with the present invention will nowbe briefly described, without in any way limiting what will ultimatelybe claimed.

An embodiment of the present invention includes a first concept, whichis a method comprising: receiving indicators from a plurality ofrespective cells, each of the indicators being indicative of adifference, if any, regarding allocation between the respective cell andneighbor cells; and, performing measurements according to the indicatorsand on the basis of configuration of a cell where the measurements areperformed.

An embodiment of the present invention also includes the method of thefirst concept, wherein at least one of the indicators is setautomatically using inter-node signaling.

An embodiment of the present invention also includes a third concept,which is a mobile device comprising: a transceiver configured to receiveindicators from a plurality of respective cells, each of the indicatorsbeing indicative of a difference, if any, regarding allocation betweenthe respective cell and neighbor cells; and, a measuring moduleconfigured to perform measurements according to the indicators and onthe basis of configuration of a cell where the measurements areperformed.

An embodiment of the present invention also includes a fourth conceptwhich is the mobile device of the third concept, wherein at least one ofthe indicators is set automatically using inter-node signaling.

An embodiment of the present invention also includes a fifth concept,which is a mobile device comprising: means for receiving indicators froma plurality of respective cells, each of the indicators being indicativeof a difference, if any, regarding allocation between the respectivecell and neighbor cells; and, means for performing measurementsaccording to the indicators and on the basis of configuration of a cellwhere the measurements are performed.

An embodiment of the present invention also includes a sixth conceptwhich is the mobile device of the fifth concept, wherein at least one ofthe indicators is set automatically using inter-node signaling.

An embodiment of the present invention includes a seventh concept, whichis a computer program product, the computer program product comprising acomputer readable medium having executable code stored therein; thecode, when executed by a processor, adapted to carry out the steps of:receiving indicators from a plurality of respective cells, each of theindicators being indicative of a difference, if any, regardingallocation between the respective cell and neighbor cells; and,performing measurements according to the indicators and on the basis ofconfiguration of a cell where the measurements are performed.

An embodiment of the present invention also includes an eighth concept,which is the computer program product of the seventh concept, wherein atleast one of the indicators is set automatically using inter-nodesignaling.

Embodiments described above can be implemented using a general purposeor specific-use computer system, with standard operating system softwareconforming to the method described herein. The software is designed todrive the operation of the particular hardware of the system, and willbe compatible with other system components and I/O controllers. Thecomputer system of this embodiment includes a CPU processor, comprisinga single processing unit, multiple processing units capable of paralleloperation, or the CPU can be distributed across one or more processingunits in one or more locations, e.g., on a client and server. A memorymay comprise any known type of data storage and/or transmission media,including magnetic media, optical media, random access memory (RAM),read-only memory (ROM), a data cache, a data object, etc. Moreover,similar to the CPU, the memory may reside at a single physical location,comprising one or more types of data storage, or be distributed across aplurality of physical systems in various forms.

It is to be understood that the present figures, and the accompanyingnarrative discussions of best mode embodiments, do not purport to becompletely rigorous treatments of the method, system, mobile device,network element, and software product under consideration. A personskilled in the art will understand that the steps and signals of thepresent application represent general cause-and-effect relationshipsthat do not exclude intermediate interactions of various types, and willfurther understand that the various steps and structures described inthis application can be implemented by a variety of different sequencesand configurations, using various different combinations of hardware andsoftware which need not be further detailed herein.

What is claimed is:
 1. A method comprising: receiving, at a userequipment in a cell, an indicator representing whether a sub-frameallocation in the cell differs from another sub-frame allocation in oneor more neighboring cells; and performing, at the user equipment,measurements based on at least the received indicator and cellconfiguration, wherein the measurements are mobility related neighborcell measurements, wherein the received indicator defines one or morereference symbols in the sub-frame allocation and the another sub-frameallocation to measure, and wherein the sub-frame allocation comprises atleast one of a multicast broadcast single frequency network sub-frameallocation and a unicast sub-frame allocation.
 2. The method of claim 1,wherein a beacon signal is received in discontinuous time periods, thebeacon signal having at least two possible phases comprising a firstphase in which the beacon signal is received a first number of timesover a first time interval, and a second phase in which the beaconsignal is received a second number of times over a second time interval,and wherein the indicator indicates whether at least two cells use acommon setting of the at least two possible phases.
 3. The method ofclaim 2, wherein the second number of times form a subset of the firstnumber of times.
 4. The method of claim 1, wherein the indicator is setautomatically using inter-node signaling.
 5. The method of claim 1,wherein the indicator is received via a common channel.
 6. The method ofclaim 5, wherein the common channel comprises a broadcast controlchannel.
 7. The method of claim 1, wherein the indicator comprises oneor more bits, and wherein the indicator represents whether a multicastbroadcast single frequency network is present in the one or moreneighboring cells.
 8. The method of claim 1, wherein the measurementscomprise beacon signal measurements, and wherein the indicator is usedby a mobile station to determine when the mobile station can reliablymake the measurements.
 9. The method of claim 8, wherein the beaconsignal comprises a reference signal.
 10. An apparatus comprising: atransceiver configured to receive an indicator representing whether asub-frame allocation in a cell differs from another sub-frame allocationin one or more neighboring cells; and a measurement module configured toperform measurements based on at least the received indicator and cellconfiguration, wherein the measurements are mobility related neighborcell measurements, wherein the received indicator defines one or morereference symbols in the sub-frame allocation and the another sub-frameallocation to measure, and wherein the sub-frame allocation comprises atleast one of a multicast broadcast single frequency network sub-frameallocation and a unicast sub-frame allocation.
 11. The apparatus ofclaim 10, wherein a beacon signal is received in discontinuous timeperiods, the beacon signal having at least two possible phases,including a first phase in which the beacon signal is received a firstnumber of times over a first time interval, and including a second phasein which the beacon signal is received a second number of times over asecond time interval, and wherein the at least one indicator indicateswhether at least two cells use a common setting of the at least twopossible phases.
 12. The apparatus of claim 11, wherein the secondnumber of times form a subset of the first number of times.
 13. Theapparatus of claim 10, wherein the indicator is set automatically usinginter-node signaling.
 14. The apparatus of claim 10, wherein theindicator is received via a common channel.
 15. The apparatus of claim14, wherein the common channel comprises a broadcast control channel.16. The apparatus of claim 10, wherein the indicator comprises one ormore bits, and wherein the indicator represents whether a multicastbroadcast single frequency network is present in the one or moreneighboring cells.
 17. The apparatus of claim 10, wherein themeasurements comprise beacon signal measurements, and wherein theindicator is used by a mobile station to determine when the mobilestation can reliably make the measurements.
 18. The apparatus of claim17, wherein the apparatus is a mobile station.
 19. A non-transitorycomputer readable medium comprising executable code which when executedby a processor provides operations comprising: receiving an indicatorrepresenting whether a sub-frame allocation in a cell differs fromanother sub-frame allocation in one or more neighboring cells; andperforming measurements on one or more reference symbols, themeasurements performed based on at least the received indicator, whereinthe measurements are mobility related neighbor cell measurements,wherein the received indicator defines one or more reference symbols inthe sub-frame allocation and the another sub-frame allocation tomeasure, and wherein the sub-frame allocation comprises at least one ofa multicast broadcast single frequency network sub-frame allocation anda unicast sub-frame allocation.
 20. The non-transitory computer readablemedium of claim 19, wherein a beacon signal is received in discontinuoustime periods, the beacon signal having at least two possible phases,including a first phase in which the beacon signal is received a firstnumber of times over a first time interval, and including a second phasein which the beacon signal is received a second number of times over asecond time interval, and wherein the at least one indicator includes anindicator that indicates whether at least two cells are using a commonsetting of the at least two possible phases.
 21. The non-transitorycomputer readable medium of claim 19, wherein the indicator is setautomatically using inter-node signaling.
 22. The non-transitorycomputer readable medium of claim 19, wherein the indicator is receivedvia a common channel.